Electrical switching and control system



Aug. 15, 1939. K SWART 2,169,821

ELECTRICAL SWITCHING AND CONTROL SYSTEM Filed Oct. 30, 1937 F762 7 FIGSsa -n r 54 L M/l ENTOR By L. K. SWART A T TORNE V Patented Aug. 15, 1939UNlTED STATES PATENT OFFICE ELECTRICAL SWITCHING AND CONTROL SYSTEMApplication October 30, 1937, Serial No. 171,915

18 Claims.

This invention relates to electrical switching devices and particularlyto circuit arrangements for controlling such devices.

It is the object of the invention to provide simple, eflicient andreliable means for controlling electrical switching devices and tofacilitate the testing of electrical lines and electrical apparatus.

It is known that high voltage disturbances are induced in open-Wirelines, such for instance as are used for communication or othersignaling, during electrical storms. The induced surges produce sharpclicks in telephone circuits and may cause false operation of electricalsignaling apparatus. To protect against such surges it is known toconnect a drainage coil across the two conductors of each open-wire lineat the point where the line connects with an entrance cable or otherprotected conductors, the mid-point of the drainage coil being connectedto ground. It is, however, necessary to disconnect the drainage coilfrom a line to enable testing of the line; and it has heretofore beenthe practice to provide pole switches for disconnecting the drainagecoils. In some cases the pole switch has been manually operated; and insome cases, where extra line conductors were available the switch hasbeen electrically controlled over the spare conductors.

This invention is a switching arrangement for disconnecting from a line,electrical apparatus normally connected thereto, the switching mechanismbeing controlled over the line or one of the lines from which thenormally connected apparatus is to be disconnected. According to theinvention, means are provided for delaying the operation of theswitching mechanism to prevent false operation responsive todisturbances such as are caused by lightning.

A feature of the invention is a switching arrangement for disconnectingfrom lines, apparatus normally connected thereto, the switchingmechanism being operatively controlled over a plurality of the lines andresponsive only to alternating current.

A further feature of the invention is a switching arrangement fordisconnecting from lines, apparatus normally connected thereto, theswitching mechanism being operatively controlled over one of said linesto disconnect the normally connected apparatus and operativelycontrolled over another of the lines to reconnect the normally connectedapparatus. The switching mechanlsm may comprise a self-locking controlrelay having an operating winding connected to one of the lines and areleasing winding connected to another of the lines.

These and other features of the invention will be more readilyunderstood by considering the operation of the various circuitarrangements shown schematically in the drawing which forms a part ofthis specification. The invention is not limited in its application tothe particular circuit arrangements herein disclosed but is in generalapplicable to any remotely controlled switching mechanism.

Referring to the drawing:

Fig. 1 shows lines LI and L2 having drainage coils DC! and D02 normallyconnected thereto,

a relay I5 for disconnecting the coils from the lines, and control meanscomprising gas-filled tubes GTI and GT2 and relays l3 and I4;

Fig. 2 shows lines L3 and L4 having drainage coils D03 and DC4 normallyconnected thereto, relays 35 and 45 for disconnecting the drainage coilsfrom the lines, and control means comprising gas-filled tubes GT3 andGT4, rectifiers 3| and 4|, and the self-locking relay 34, 44;

Fig. 3 shows lines L5 and L6 having drainage coils DC5 and DCG normallyconnected thereto, relays 55 and for disconnecting the drainage coilsfrom the lines, and control means comprising relays 54, 64 and 56.

Consider first the arrangement shown in Fig. 1, in which drainage coilsDC! and DC2 are normally connected through contacts of relay I5 to theconductors of lines LI and L2. The gasfilled tubes GTI and GT2 arethree-element coldcathode tubes which, with no biasing potential, becomeconductors when over volts is im pressed across the control elements. Abiasing battery II is shown connected to the lower element of tube GTI,which bias may be large enough to reduce the operating potential of thetube GTI to as low as 20 volts. One conductor of line Ll is connectedthrough condenser l0 and biasing battery H, if any, to one of thecontrol elements of tube GTI and the other conductor of line Ll isconnected through resistor l2 to the other control element of tube GTI.Whenever test of either or both of lines LI and L2 is desired, a sourceof alternating current of high enough potential to cause breakdown oftube GTI is impressed across the conductors of line Ll. Relays l3 and Mare thereupon operated by current in the circuit traced from thenegative pole of battery Bl, lower element or cathode of tube GTI,middle element or anode of tube GTI, through the windings of relays l3and I4 in series to the positive pole of battery Bl. Relay I3 is avibrating relay, the closure of its front contact being effective tohold relay i t and cause the deenergization of tube GT! and release ofrelay H3 in Well-known manner. The operating potential not having beendisconnected, the tube GTI and relay i3 reoperate; and relay i3continues to operate and release as long as the breakdown potential isimpressed across line LI. Relay I i remains operated as long as relay I3is vibrating, the winding of relay l4 being energized by currentcharging condenser 9 each time relay i3 releases. Relay M opens thenormally closed short circuit across condenser 19 and across the controlelements of tube GT2 and connects battery B! across condenser l9. Assoon as condenser i9 is charged to a potential high enough to causebreakdown of the tube, relay i5 is energized in a circuit from thenegative pole of battery Bl, through the front contact of relay l i,resistor I l, cathode and anode of tube GT2, and through the winding ofrelay 15 to the positive pole of battery Bl. The delay in energizingtube GT2 prevents the operation of relay E5 in case the tube GT! andrelays i3 and I4 respond to transient disturbances, such for instance asare caused by lightning. Relay l5 disconnects drainage coils DC! and D02from lines LI and L2 thereby enabling the application of a directcurrent test to either or both of these lines. If line Li is tested thetesting current is superimposed on the alternating currentwhich iscausing the vibration of relay [3. When the test is completed and thealternating current source is disconnected from line L, the tube GT2becomes deenergized, relay l3 cannot reoperate, and relay Hi releases.The release of relay M closes the short circuit across the controlelements of tube GT2 causing the deenergization of the tube and therelease of relay l5. Relay l5 may be a multicontact relay and controlthe connection of drainage coils to other lines in addition to lines LIand L2.

Referring now to the arrangement shown in Fig. 2, drainage coils DC3 andD04 are normally connected through contacts of relays 35 and 45 to theconductors of lines L3 and L5. Relays 35 and 55 are controlled by aself-locking relay comprising armature 39 and two coils 3t and M. Coil34 is operatively connected through the two-element gas-filled tube GT3and rectifier 3| in series with condenser 30 across the conductors ofline L3; and coil 4 is operatively connected through the two-elementgas-filled tube GT6, and rectifier M in series with condenser 4i! acrossthe conductors of line L6. The armature 49 is held by spring 38 ineither of its positions when once moved to either of these positions bythe temporary energization of coil 3 or coil 54. Each of the rectifiers3! and 4! comprises four rectifying elements of the copper-oxide typeconnected to provide full wave rectification. Biasing batteries 36 and3'! and biasing batteries 15 and 1'! may or may not be provided,depending upon the rela tion between the potential impressed acrosslines L3 and L4 and the potential which is effective to cause breakdownof tubes GT3 and GT4. The resistors '38 and resistors 23 are providedonly in case biasing batteries 36 and Si and biasing batteries it and i?are provided. When test of a line L3 or L4 is desired, a source ofalternating current of required potential is temporarily impressedacross the conductors of line L3. As soon thereafter as condenser 33 ischarged tothe breakdown potential, tube GT3 breaks down and coil 34? isenergized. Armature Z9 is thereupon attracted to close circuitsincluding battery B2 for operating relays 35 and 55. Relays 35 and .5disconnect drainage coils D03 and D05 from lines L3 and LG. Since thearmature 49 is retained in its right-hand position by spring 38, thealternating current source which effected the breakdown of tube GT3 isdisconnected so that the tube GT5 and coil 34 are deenergized. A sourceof direct current may then be connected to either of lines L3 and L4 fortesting. When the testing of the lines is complete, the source ofalternating current is momentarily impressed across the conductors ofline L45. As soon thereafter as condenser '33 is charged to thebreakdown potential, tube GT4 breaks down and coil 44 is energized,armature 39 being moved to its leftband position. The resulting releaseof relays 35 and 45 reconnects the drainage coils DC3 and DCQ to linesL3 and L4. Upon termination of the application of the alternatingcurrent source to line L4 the tube GT8 and coil M are deenergized.Obviously, a single multicontact relay can be substituted for relays 35and d5; furthermore, the connection of drainage coils to other lines canbe controlled over lines L3 and L l. The resistors 32 and 42 control thecharging of condensers 33 and E3 to provide the desired delay in thebreakdown of tubes GT3 and GT4 so as to prevent false operation due tolightning or other transients.

Referring now to the arrangement shown in Fig. 3, drainage coils DC5 andD05 are normally connected through contacts of relays 55 and 65; to theconductors of lines L5 and L6. The operation of relays 55 and 65 todisconnect the drainage coils from lines L5 and L5, and from other linesif desired, may be effected by impressing a source of alternatingcurrent either across the conductors of line L5 or across the conductorsof line L6. The windings of relay 54 are connected in series withrectifier elements 55 and 52 and in series with condenser 58 across theconductors of line L5 and the windings of relay 54 are connected inseries with rectifier elements 6% and 62 in series with condenser 66across the conductors of line L5. If and when a source of alternatingcurrent of high enough potential is impressed across the conductors ofline L5, relay 54 operates, one of its windings being energized duringonehalf or" each cycle and the other of its windings being energizedduring the other half of each cycle. As soon as relay 56 operates itcloses a circuit for operating relay 56, and relay 56 closes circuitsfor operating relays 55 and $5. As long as the source of alternatingcurrent is connected to line L5, relays 55 and 65 are held operated, sothat a direct current test may be applied to either of lines L5 and L6or to any other line, the drainage coil of which is disconnected by theoperation of relay 55 or 35. Alternatively, a source of alternatingcurrent of high enough potential may be impressed across the conductorsof line L5 instead of across the conductors of line L5. In this caserelay 64 operates, its windings being alternately energized during eachhalf-cycle. Relay 5 i closes a circuit for operating relay 56 and relay5% closes the circuits for operating relays E5 and 55. Relay 56 isprovided to introduce a delay in the operation of relays 55 and t5 so asto prevent false operation in case relay 54 or relay 64 is temporarilyoperated by lightning or other transient disturbances. If relays 5d and64 are slow in operating, relay 56 may be omitted, in which case relays55 and 65 are directly controlled by relays 54 and 64.

lines, a protective device for each line normally connected therewith, arelay for disconnecting said devices from said lines, means controlledover one of said lines for operating said relay, said means comprising arectifier and an electromagnet, and means controlled over another ofsaid lines for releasing said relay, the last-mentioned means comprisinga rectifier and an electromagnet.

14. In combination in. an electrical system, lines, a conductive devicefor each line and normally connected therewith, a relay fordisconnecting said devices from said lines, means controlled over one ofsaid lines for effecting the operation of said relay, said meanscomprising a condenser, rectifier and electro magnet connected in seriesto the conductors of said one line, and like means controlled overanother of said lines for effecting the release of said relay.

15. In a combination according to claim 14, means comprising a condenserand a two-element gas-filled tube connected in series with thefirst-mentioned electromagnet and like means connected in series withthe second-mentioned electromagnet for delaying the operation of saidelectromagnets.

16.111 combination in an electrical system, lines, a protective devicefor each line and normally connected therewith, a relay fordisconnecting said devices from said lines, means con- 'nected to andoperatively controlled over one of said lines for efiecting theoperation of said relay, and like means connected to and operativelycontrolled over another of said lines.

17. In combination in an electrical system, lines, a protective devicefor each line and normally connected therewith, a relay fordisconnecting said devices from said lines, means operatively controlledover one of said lines for effecting the operation of said relay, saidmeans comprising a condenser, rectifier and relay connected in series tothe conductors of said one of the lines, and like means operativelycontrolled over another of said lines for effecting the operation ofsaid relay.

18. In combination in an electrical system, lines, a protective devicefor each line and normally connected therewith, a relay fordisconnecting said devices from said lines, means peratively controlledover one of said lines for effecting the operation of said relay, saidmeans comprising a condenser, rectifier and relay conneoted in series tothe conductors of said one of the lines, like means operativelycontrolled over another of said lines for effecting the opera tion ofsaid relay, and means for delaying the operation of said relay.

LELAND K. SWART.

